Labyrinth seal



Feb. 26, 1952 WINTHER 2,587,077

LABYRINTH SEAL Filed June 25, 1948 Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE LABYRIN Anthony Winther, Kenosha, Wis., assignor to Martin P. Winther, as trustee pp icat o J m: 25., 8 Seria No- 5,191

2Claims. 1

This invention relates to labyrinth seals, and with regard to certain more specific features, to such seals for rotary apparatus.

Among the several objects of the invention may be noted the provision of an improved form of labyrinth seal for apparatus which has relatively rotary parts between which is carried a fluid materal such as water, oil, or fiowingmixtures and the like; the provision of a seal of the class described for large radii of action in which, although wide non-rubbing clearances are provided, there is insurance against escape of fluideither while the apparatus is rotary or stationary; and the provision of a seal of this class which is easy to manufacture, install and maintain. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which oneof various possible embodiments of the invention is illustrated,

Fig. l is an axial section through apparatus embodying the invention; and

Fig. 2 is an enlarged detail of part of the lefthand sealing parts shown in Fig. 1.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

In the drawings and in the following description, inly such parts of exemplary apparatus embodying the invention are enumerated and discussed as are necessary to a full understanding. Referring now more particularly to Fig. 1, there is shown at numeral l the flanged end of a crankshaft to which is attached the inner magnetic drum 3 of a field member. Drum 3 carries a toroidal field coil 5 and attached magnetic rings 1 and 9 having interdigitated magnetic pole extensions II and I3, respectively. The members thus far described rotate as a unit.

At numeral [5 is shown a driven shaft. This is supported within the drum 3 on bearing I1 and piloted in a bearing l9 carried in the end of the crankshaft l. Splined to the shaft i5 is a hub assembly 2|, to which is bolted at 23 a two-part casing 25 made up of assembled members 21 and 29. In one of the members 21 is carried a magnetic inductor drum insert 3|, which surrounds the pole members I I and I3 at a magnetic gap 33. A flange 34 of the insert 3| is held between the parts 2'! and 29 by means of fasteners 35. The parts of the members 21 and 29 are for certain applicationspreferably nonmagnetic, being in the present case formed of aluminum. However, this is not necessary in all applications of the invention. The members 21 and 29 provide closure head at opposite ends of the field member constituted by the parts 3l3. They also are formed to provide internal reservoirs 35 for fluid which it is desired to carry in the apparatus.

on opposite sides of the magnetic rings 1 and 9 are carried side rings 31 and 39, respectively. These are preferably, though not necessarily, nonmagnetic (aluminum for example). To prevent leakage of fluid (such as oil, water or magnetic mixtures) carried in the reservoirs 35, the adjacent members of each pair of elements 21, 31 and 29, 39 are formed as labyrinth seals 2 and 4. It is to improvements in these seals that the present invention is directed. Ordinarily such seals are formed by cutting staggered axial (cylindric) grooves alternately in a pair of relatively rotary members and interdigitating the cyli dric c l ars t us left.

The present invention comprises the provision of conic-a1 grooves 4| and 43 forming conical collars 45 and 41 respectively. The sides of these collars 45 and 41 slope at about 10 to the axis of rotation of the coaxial supporting shafts. This leaves a complementary angle of outside of each collar With respect to the radial plane of the respective supporting parts. The radial spacing or pitch between successive conical collars 45 or 41 is such that with a given depth E of groove 4| or 43 used, the overlap 0' will preferably be approximately one-third of the spacing between the inner faces 49 and 5| of members such as 21 and 31 for example (see Fig. 2). This makes the overlap 0 approximately one-half of the common depth of all flaring frustums constituted by the collars 45 and 41.

While the thickness of the wall of each conical cup. is a. matter of choice, it is preferable that each wall be as thin as is consistent with proper rigidity and ease of manufacture, as called for by the particular material composing the cups. In the present case this is aluminum and a 5% inch wall thickness is satisfactory for a distance between walls 49 and 5| of inch. This makes the heighth of each cup about inch. The reason for using a minimum wall thickness is to accommodate as many interdigitated cups as possible in a given radial increment.

In view of the above, it will be seen that the collars 45 and .41, considered as hollow frustums of cones (or cups), have their open ends larger than their closed ends, said open ends being interdigitated. The arrangement is such that there is definite clearance and no rubbing between the open edge 53 of any cup and the adjacent one. The result is a completely free-running seal with no rubbing friction at any relative speed at any radius. Hence the device is applicable to large sealing radii in high-speed apparatus.

In operation the driving shaft '1' drives the driven shaft i5 by reason of an electromagnetic coupling between the field poles ll, l3 and the inductor drum 3|. This may occur with some or no slip. The exact operation in this respect is not of importance to the present invention. It

sufiices to say that in various forms of apparatus of the class concerned, a liquid isdesired between the field and inductor members. This may be water, oil, creamy mixtures of magnetic particles and oil, or the like. For instance in a dynamometer application cooling water might be used and in a magnetic coupling a magnetic slurry might be used. Such liquids are spun outwardly under rotation. Under stationary conditions the liquid tends to gravitate to the bottom of the case- 25. In doing so, it drops onto the outermost collars 41, which act as V-shaped channels guiding the fluid around to the bottom without possibility of escape unless the channel overflows. Any overflow that may occur from the outermost channel or channels is taken up by more inwardly located ones and a suificient number are provided to assure that cascading cannot occur over all collars before all the liquid to be accommodated in the bottom of the case has found its way down to that point.

When the apparatus starts from rest, any collection of liquid at the bottom that has found,

its way into the bottommost portions of thechannels 4| and 43 clings to collars 45 and 61. As these rotate, the liquid under centrifugal force, instead of being trapped within the collars, seeks its way outward along the sloping inner conic surfaces. Thus it cascades radially outward, finally finding its way into the reservoirs and into the magnetic gap 33.

In the above description, the details of Fig. 2"

have'been recited in connection only with the left-hand-seal, but it is to be understood that the same details apply to the right-hand seal. In fact, Fig. 2 could be considered to represent a structure in either the left or the right-hand.

of the invention, it is intended that all matter] contained in the above description or shown in' the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A labyrinth seal for use between relatively rotary coaxial parts, said parts providing an annular reservoir for flowable non-gaseous material, said rotary parts having axially spaced and radially arranged opposing faces, comprising a series of concentrically arranged conical open-ended rigid frustums extending from one part away from the axis and coaxial therewith and positinned inside the reservoir, and a second series of oppositely directed hollow concentrically arranged conical open-ended rigid frustums extending from the other part away from'the axis and coaxial therewith and also positioned inside the reservoir, the sides of the frustums sloping with respect to the axis of rotation an amount substantially smaller than their complementary slopes with respect to a radial plane, whereby the open ends of the frustums may be interdigitated a substantial amount while allowing large enough clearances therebetween that any of said flowable material that may enter between the frustums during standstill will freely return to the reservoir under centrifugal force induced by rotation of the rotary members.

2. A labyrinth seal for use between relatively rotary coaxial parts, said parts providing an annular reservoir for flowable magnetic material of a non-gaseousnature, said rotary parts having axially spaced and radially arranged opposing nonmagnetic faces, comprising a series of concentrically arranged conical open-ended rigid nonmagnetic frustums extending from one part away from the axis and coaxial therewith and positioned inside the reservoir, and a second series of oppositely directed hollow concentrically arranged conical open-ended rigid nonmagnetic frustums extending from the other. part away from the axis and coaxial therewith and also positioned inside the reservoir, the sides of the frustums sloping with respect to the axis of rotation an amount substantially smaller than their complementary slopes with respect to a radial plane, whereby the open ends of the frustums maybe interdigitated a substantial amount while allowing large enough clearances therebetween that any magnetic flowable material which. may escape from the reservoir and enter between the frusturns during standstill may freely return to the reservoir under centrifugal force induced by rotation of the rotary members.

ANTHONY WINTI-IER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

